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Topic: IDEA: single pixel CRT magnet sensor (Read 791 times)

This is simply an idea which has never been proven by me, and I'm curious what kind of thoughts this community might have.

We all know how CRT monitors are affected by magnets, but what we (me) don't know is how a CRT pixel's analog status might change when a magnet is present. If we could not only apply variable voltage to the pixels of a CRT screen, but also monitor the change or 'status' of each pixel as a magnet is present, perhaps we could track the movement of the magnet as it travels around the CRT screen. How is this useful? Well, for pocket PC type devices that use a plastic pen and resistance/capacitance sensors, we can completely eliminate the pressure sensor and use the pixels to track the 'magnetic point' of the pen. This would provide a lower cost solution for pen based pocket-pc's.

I know a CRT generally uses a tube to illuminate the pixels, but perhaps this can be substituted by an array of LED's. Current LCD screens in cell phones, flat screens, and portable devices do not react to magnetism in the same way that CRT's do, so I wonder if it's possible to get this effect on a small size screen.

Thoughts?

Edit: After further researching the function of a CRT monitor, I now see that the magnetic reaction is a result of changing the magnetic signal emitted by the tube. I suppose this idea is shot now.

[...] perhaps we could track the movement of the magnet as it travels around the CRT screen. How is this useful? Well, for pocket PC type devices that use a plastic pen and resistance/capacitance sensors, we can completely eliminate the pressure sensor and use the pixels to track the 'magnetic point' of the pen. This would provide a lower cost solution for pen based pocket-pc's.

And how expensive do you think that the pockets for a CRT would be (Would look bad as well, both the pockets and the displays that went rainbow color and had to be degaussed regularly).

I never completely understood how the CRT works until I looked this up and found a great pdf with all the info. I like to try and re-invent certain technologies at lower cost and right now I'm really focused on touch-sensing. The touch screens available today are still too expensive for my particular application, so I've been trying to come up with an accurate work-around. I've even considered using an array of phototransistors mounted behind an OLED screen to monitor the position of light reflected from the pixels of the screen off of the object or pen point touching the screen, but there were too many problems with ambient light affecting the signal. Oh well, back to the drawing board!